Plumbing is one of those things you don't really think about until it breaks. In Greece right now, the financial plumbing is being made painfully visible. David Kestenbaum, of our Planet Money team, says it's a lesson in the hidden things that keep an economy together.

DAVID KESTENBAUM, BYLINE: About a week and a half ago, Miltiades Gkouzouris was driving home with his family to Athens when the news came on the radio. The government had been unable to reach a bailout deal with the rest of Europe, so it was closing the banks for an undetermined period of time.

MILTIADES GKOUZOURIS: Oh, my God, was the first thing that came up to my mind. And the second thing was to fill the car with gasoline. So we stopped immediately at the first gas station, and we filled it up to the neck.

KESTENBAUM: There was the restriction you've probably heard about. People could only get 60 euros a day out of the ATMs. But there was another potentially bigger thing also designed to keep money from leaving the banks - the pipes that carried money out of the country, those were also being closed down. This seemed very, very bad to him. Gkouzouris works with companies that import things - air conditioners, radios, food. And you can't import something if you can't pay for it.

GKOUZOURIS: Even if I want to send 1 euro to whatever, outside Greece, it's impossible.

KESTENBAUM: One of his clients imports beans. The guy can't bring in any beans.

GKOUZOURIS: In a couple of weeks when his stock is going to run out, then he has a real problem.

KESTENBAUM: And anyone in Greece who wants beans will also have a problem.

GKOUZOURIS: For sure, yes because you're going to walk into a supermarket and there's going to be only local beans. And the production of beans in Greece is, like, 12 percent of the total demand, of the total amount we use here, so it's nothing.

KESTENBAUM: No country can really exist on its own these days. Greece imports medicine, feed for farmers' animals. Gkouzouris figures Greece has maybe three, maybe four weeks, before stores start running out of things.

GKOUZOURIS: And that's going to be due to the fact that people, in a couple of weeks, will start panicking and buying like crazy. So that's when I believe that the supermarkets will run out of products, and then the system will be really clear and visible to everyone, the system collapse.

KESTENBAUM: You don't realize how important banks are until you try to live without them. Greece's neighbor, Cyprus, tried a couple years back. Cyprus, which is also on the euro, had to close its banks while it was trying to work out a deal with Europe. Panicos Demetriades used to run Cyprus's central bank. He says some people figured it wouldn't be so bad.

PANICOS DEMETRIADES: They said to me - some of them said to me - well, you know, let's keep them closed for two months. So what? So the same politicians, a week later, were coming back to me and asking me, how soon can you reopen the banks, how soon can you reopen the banks?

KESTENBAUM: Cyprus managed to get its banks open after a couple weeks, but there were all sorts of restrictions for years. Once you close the financial pipes, you have to reopen them slowly. And Demetriades says, as bad as Cyprus's crisis was, Greece's situation is worse.

DEMETRIADES: Banks are so integrated. You cannot - not a single economic transaction can take place without banks. So the minute that they're out of the picture, there's complete paralysis. And this is where they are now.

KESTENBAUM: Miltiades Gkouzouris, the businessman who works with importers, says he has stockpiled three weeks of food.

GKOUZOURIS: And after that, I mean, if I see that the situation escalates somehow then I'm going to just get the family and get out of the country.

KESTENBAUM: Get out of the country?

GKOUZOURIS: Yeah, yes. I don't want to stay here and experience this.

KESTENBAUM: He told his wife to keep the car full of gas so they can reach the border. David Kestenbaum, NPR News. Transcript provided by NPR, Copyright NPR.